I killed Vulpes Inculta and his men in Nipton which made me vilified by Caesar's Legion. I was greeted by two legionary assassins shortly after. When I got to Ranger station Charlie I noticed the legionaries around that area were not hostile towards me. I haven't played the game in very long while so I'm not sure if this is supposed to be normal or a bug, I remember stealing something was enough to bring down a rain of bullets on me.

The only armor I equipped so far is the one Doc gave me, and just for a quick test I used the console to vilify myself with the NCR then fast traveled to Mojave Outpost and same thing.

I should mention attacking them will make them hostile but the rest of the legion just won't care.

Do you have any mods?

Nope. My game is vanilla with all the DLC installed except for Courier's Stash.